荔枝酒酿造中酿酒酵母同步代谢醋酸的研究

Synchronous Metabolism of Acetic Acid by Saccharomyces cerevisiae in Litchi Wine Brewing

以具有强降酸及耐高浓度酒精能力的酿酒酵母为出发菌株,研究荔枝酿酒过程中同步代谢挥发醋酸的机制。结果表明:酿酒酵母代谢醋酸的量随着起始醋酸浓度的增加先升后降,在初始醋酸浓度为1.5 g/L时,酿酒酵母对醋酸的代谢率最大达48.0%,发酵结束时醋酸含量为0.78 g/L。酿酒酵母代谢醋酸的最快速度是在对数期。醋酸对酿酒酵母主要代谢产物的影响表现为酿造过程中产生了较少的甘油、较高的乙醛和乙醇。丙酮酸脱羧酶(PDC)、乙醇脱氢酶(ADH)、乙醛脱氢酶(ALDH)及乙酰辅酶A合成酶(ACS)酶比活性的变化与乙醇、甘油、乙醛及醋酸含量的变化相一致。酿造过程中存在过量醋酸时,酿酒酵母ACS酶比活性进一步增强,说明过量醋酸的代谢与通过调节酿酒酵母提高其ACS酶活性有关。

In order to reveal the metabolic mechanism of removal acetic acid during litchi wine fermentation in oenological conditions, Saccharomyces cerevisiae, which has the abilities of strong metabolism of acetic acid as well as high tolerance to high levels of alcohol, was inoculated at the fermentation matrix of lychee juice supplemented with different initial concentration of acetic acid. The results indicated that the amount of acetic acid metabolized by Yds101 increased with initial acetic acid concentration increasing and then decreased. While litchi juice supplemented with 1.5 g/L acetic acid before fermentation, at the end of fermentation, the content of acetic acid was 0.78 g/L and decreased by 48.0%. This was the optimal metabolic rate of all the tested samples.The fastest consumption rate of acetic acid was in the exponential phase. The effects of acetic acid on the metabolic products of yeast were that： There was less glycerin and more acetaldehyde and ethanol than these unsupplemented with acetic acid during the fermentation. The specific activity variation of pyruvate decarboxylase,ethanol dehydrogenase, acetaldehyde dehydrogenase and acetyl-Co A synthetase were consistent with the content changes of ethanol, glycerol changes and acetaldehyde. Under excessive concentration of acetic acid, the specific activity of acetyl-Co A synthetase further enhanced, which suggesting that improving the specific activity of ACS by stimulating Saccharomyces cerevisiae was related with excessice acetic acid.